Antenna systems are widely used in both ground based applications (e.g., cellular antennas) and airborne applications (e.g., airplane or satellite antennas). For example, so-called “smart” antenna systems, such as adaptive or phased array antennas, combine the outputs of multiple antenna elements with signal processing capabilities to transmit and/or receive communications signals (e.g., microwave signals, RF signals, etc.). As a result, such antenna systems can vary the transmission and/or reception pattern of the communications signals.
For example, each antenna element typically has a respective phase shifter and/or gain element associated therewith. The phase shifters/gain (i.e., amplitude control) elements may be controlled by a central controller, for example, to adjust respective phases/amplitudes of the antenna elements across the array. Thus, it is not only possible to steer the antenna beam, but it is also possible to perform beam shaping and/or adjust beam width (i.e., “spoiling”) to receive or transmit over different areas. Another advantage of phased array antennas is that the array of elements may be arranged in sub-groups, and each of the sub-groups used for different antenna beams to thus provide multi-beam operation.
One example of a phased array antenna is disclosed in the above-noted U.S. patent application Ser. No. 10/060,497, which is assigned to the present Assignee. This application discloses a phased array antenna which includes a substrate and a plurality of spaced apart phased array antenna elements carried by the substrate and arranged along an imaginary Archimedean spiral. The imaginary Archimedean spiral includes a plurality of levels, and a spacing between adjacent pairs of phased array antenna elements along the imaginary Archimedean spiral is substantially equal to a radial spacing between adjacent levels. Among other advantages, this antenna configuration reduces occurrences of grating and/or high gain side lobes, yet is relatively easily scalable for numerous applications.
The advantages of such a spiral antenna element configuration may also be extended to relatively large antenna configurations. By way of example, the above-noted U.S. Pat. No. 6,456,244, which is assigned to the present Assignee, discloses a phased array antenna including a plurality of aperiodic antenna element subarrays, and the subarrays are in turn arranged in an aperiodic array. The subarrays may be arranged in the form of spirals, for example, or in other geometric shapes, as disclosed in the above-noted U.S. application Ser. No. 10/303,580, which is also assigned to the present Assignee. The antenna may similarly perform amplifying, phase shifting and beam forming on transmitted or received signals with reduced side lobes. In addition, because of the aperiodic configuration, the electronic circuitry can be mounted between antenna elements.
As the size and complexity of phased array antennas grows, so too does the need for efficient control circuitry for managing the beam steering and beam shaping data which has to be communicated to hundreds or even thousands of elements. One particularly efficient phased array antenna control architecture is disclosed in U.S. Pat. No. 6,573,863 which is assigned to the present Assignee. In particular, this application discloses a phased array antenna system which includes a plurality of antenna element controllers connected to the phased array antenna elements, and at least one higher level controller connected to the plurality of antenna element controllers. The at least one higher level controller and/or lower level antenna element controllers may perform a processing operation on a first portion of a received multi-bit command message before receiving all bits of the multi-bit command message. This configuration advantageously provides a more efficient usage of processor time and may therefore reduce beam steering latency time and increase beam steering update rates.
Despite the significant advancements provided by the above-noted phased array antennas, further control features may be desired in certain applications, such as for communications applications, for example.